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Title: Where and how does the solar dynamo generate the toroidal field?
Plain: The Sun's magnetic cycle comes from a dynamo (gas motions regenerating the magnetic field), but whether it operates near the bottom of the convection zone or throughout it is unknown.
Precise: Determine whether the solar cycle is a Babcock-Leighton flux-transport dynamo with toroidal (east-west) field generated and stored in the tachocline ($r \sim 0.7\,R_{\mathrm{sun}}$) or a distributed dynamo in the convection zone. Answer: a model reproducing the butterfly diagram, the 22-year magnetic cycle period, polar-field reversal and helioseismic flows.
Settled by: Helioseismic detection of the toroidal field or its flow signatures at depth, together with a simulation reproducing the cycle at solar luminosity and rotation.
Kind: phenomenon
Answer type: mechanism
References: (empty)
Literature status: open
Status note: (empty)
Posed since: 1955